Noise insulation
Posted: Mon Feb 05, 2024 3:40 pm
by cjaeger
Just started test flying Sonex #1571 LN-SNX in Norway. It’s a blast to fly. I notice significant noise from the flat fuselage bottom plates while taxiing and there is also fuselage noise during flight. Has anyone on the forum tried out any means to reduce this issue?
Re: Noise insulation
Posted: Mon Feb 05, 2024 3:53 pm
by Bryan Cotton
I wear a headset. Weight is the enemy.
Re: Noise insulation
Posted: Mon Feb 05, 2024 4:54 pm
by daleandee
Bryan Cotton wrote:I wear a headset. Weight is the enemy.
I use Clarity Aloft … weight is the enemy! 8~)
Re: Noise insulation
Posted: Tue Feb 06, 2024 4:15 am
by cjaeger
I fly in controlled airspace so use a headset. Still cant’t help noticing the ‘tin can’ noise from the flat parts of the fuselage. I was thinking of putting some lightweight foam on the inside of the largest flat areas. Anyone tried this or other noise reduction measures without adding too much weight?
Re: Noise insulation
Posted: Tue Feb 06, 2024 8:10 am
by GordonTurner
I remember someone used angle pieces, just 1x1x.025 or maybe less, attached diagonally across panels with double sided tape. Effective, but no analysis of how these may concentrate stress at their ends.
Re: Noise insulation
Posted: Tue Feb 06, 2024 10:48 am
by builderflyer
cjaeger wrote:Just started test flying Sonex #1571 LN-SNX in Norway. It’s a blast to fly. I notice significant noise from the flat fuselage bottom plates while taxiing and there is also fuselage noise during flight. Has anyone on the forum tried out any means to reduce this issue?
Pneumatic tailwheel tire for ground operations and a Halo in the ear headset for ground and air operations. Both combine to make a significant reduction in “noise” without adding any weight.
Art,Sonex taildragger #95,Jabiru 3300 #261
Re: Noise insulation
Posted: Tue Feb 06, 2024 10:55 am
by WaiexB22
GordonTurner wrote:I remember someone used angle pieces, just 1x1x.025 or maybe less, attached diagonally across panels with double sided tape. Effective, but no analysis of how these may concentrate stress at their ends.
I saw this on another build and I am considering doing this to reduce the oil canning noise from the tail. I just don’t know about double sided tape. If they come loose they could interfere with the controls. I am considering fully riveting them, or double sided tape with one rivet at each end.
Re: Noise insulation
Posted: Sat Feb 10, 2024 3:26 pm
by rhw5548
I installed the angle pieces.. still building
I like the 2 Rivet Idea
Re: Noise insulation
Posted: Sat Feb 10, 2024 5:45 pm
by mike.smith
WaiexB22 wrote:
GordonTurner wrote:I remember someone used angle pieces, just 1x1x.025 or maybe less, attached diagonally across panels with double sided tape. Effective, but no analysis of how these may concentrate stress at their ends.
I saw this on another build and I am considering doing this to reduce the oil canning noise from the tail. I just don’t know about double sided tape. If they come loose they could interfere with the controls. I am considering fully riveting them, or double sided tape with one rivet at each end.
I have had mine in place for 9 years. I used the 3M VHB (very high bond) double sided tape. I stuck them on with double sided carpet tape during my build, and one day I found two of them on the floor! Took them all off and re-stuck with the VHB. It’s pretty powerful stuff.
http://www.mykitlog.com/users/display_l … 181&row=11
http://www.mykitlog.com/users/display_l … 191&row=10
http://www.mykitlog.com/users/display_l … 8137&row=8
Re: Noise insulation
Posted: Sat Feb 10, 2024 6:07 pm
by GordonTurner
In my TLAR engineering expertise…the risk of riveting is creating stress points in an in-engineered way. The tape spreads the load evenly over the whole area, and probably has a little give in the bond. I know stresses will transmit to the ends of these trusses.
Re: Noise insulation
Posted: Sun Feb 11, 2024 12:41 am
by WaiexB22
Mike. Thanks for the feedback. I can’t argue with 9 years of the tape. I think I have some gopro mounts that use that stuff and it is super strong. I think I will get a roll and go that way.
Re: Noise insulation
Posted: Sun Feb 11, 2024 3:00 am
by peter anson
About 8 or 9 years ago I spent a lot of time trying different methods of reducing noise in the cockpit by fitting insulation. See https://www.sonexaus.org.au/galleries/building-tips/cockpit-noise/ on the Sonex Australia site for more details. Unfortunately the article I wrote has lost some of it’s formatting making it difficult to interpret the data so to summarise, nothing worked very well. I could get some noise reduction at low RPM and high RPM but hardly any useful effect at cruise speed. I think a muffler on the engine would help (Jab 3300) but there is barely enough space in the cowl to fit one. At present I have the oil cooler fitted where the muffler would normally fit on the Jabiru engine. If I could fit the muffler in that location I think it would have to be heavily modified to fit inside the cowl.
Peter